由自下而上的思路直接合成的低维材料，具备原子级平滑的表面和界面。其优异的性能使得它们有望成为集成电路领域得以迈入新时代的突破口。然而，当前大多数合成低维材料的工艺仍然是预先设定生长参数，并在生长完成后对样品进行表征，对于生长的具体过程缺乏实时了解，只能采用开环控制。这种情况下，对于材料合成的精准控制难以实现。本工作以石英衬底上碳纳米管水平阵列的化学气相沉积法合成为出发点。利用时变外电场诱发生长中的碳纳米管进行重新成核，是引入碳纳米管内手性结及生长高纯度半导体性碳纳米管阵列的有效方法。为此，有必要设计和制作能够在高温环境下稳定工作的电路。经过反复尝试，本文开发了以嵌套光刻将Mo金属电极设置在催化剂周围，并利用超顺排碳纳米管导电胶带及六方氮化硼/碳纳米管耐高温导线实现金属电极与外电路在生长过程中全程连接的耐高温探测-反馈电路的工艺。同时，本文研究和总结了不同材料在通电时对生长的影响，发现了金属Mo在未通电时对生长的影响较轻微，但在通电时对生长的抑制作用急剧增加。耐高温探测-反馈电路具有探测电极与反馈电极两对电极。将沟道内填充满催化剂的探测电极与锁相放大器串联，可原位监测碳纳米管无序网络的渗流信号。利用Mo电极在通电时对生长的抑制作用，向反馈电极加-40 V直流电压可实现生长的即时终止。通过将原位探测到的电流信号及在不同时刻终止生长的结果进行比对，本文得到了碳纳米管水平阵列生长时间线的统计分布。根据该统计，碳纳米管水平阵列的生长窗口（约5 s）短于其起始时间在不同生长批次间的涨落（10 s左右），证明了原位监测对于精确的生长控制而言的必要性。 进一步，向沟道内填充一半催化剂的探测电极输入低占空比的探测电压序列，可原位测量水平阵列刚生长出来并接触到探测电极后导致的电流阶跃变化，得到阵列生长开始的准确时间。在此同时，或少许延时后，向反馈电极加负脉冲电压即可产生脉冲电场使得生长中的碳纳米管产生手性转变。如果不加延时，则生长产物为纯半导体碳纳米管阵列；如果加入延时，则产物为金属-半导体管内手性结阵列，且手性结的位置可由延时调控。利用上述可编程流程，本文实现了碳纳米管阵列的智能合成。相较传统方法，智能合成对于异质结位置的时间分辨控制能力提高了20到100倍。
The bottom-up approach to directly synthesizing low-dimensional materials with atomically smooth surfaces and interfaces is promising to boost integrated circuits into the next generation. However, without any monitoring of the actual synthesis status, current synthesis methods are mostly open-loop-controlled; that is, the synthesis conditions are preset and the synthesis results are examined ex situ. It is hard to provide precise control of the synthesis. This thesis is based on the growth of CNT horizontal arrays on quartz substrates via chemical vapor deposition. The electro-renucleation approach; that is, the chirality of the growing CNTs is twisted by an applied time-varying electric field, is promising to provide highly pure semiconducting CNT arrays. It is thus necessary to design and build a circuit working stably at high temperature. To biuld high-temperature-tolerant sense-and-respond circuits, Mo electrodes are patterned by UV lithography and deposited about the catalysts and connected to external circuits during the growth progress with SACNT tapes and h-BN/CNT wires. The effects on the growth of CNT produced by different materials electrode are also studied. It is found that the Mo electrodes affect the growth slightly but suppress the growth intensively when a voltage is applied to them. The sense-and-respond circuit is composed of the sensing electrodes and the responding electrodes. The catalyst is deposited in between the two sensing electrodes which are connected to a lock-in amplifier. The formation and evolution of the disordered CNT network is monitored by sensing the impedance change. The growth can be terminated immediately by applying a strong direct voltage (-40 V) to the Mo responding electrodes, whereas the conventional methods of precursor turnoff and temperature decrease always generate a deferred termination. Statistics of the timeline of the growth are obtained by using the E-field termination method upon different time. It is found that the time window of the array growth is smaller than the variances of the start time between batches, which implies that without the in-situ sensing, accurate control of the growth is impossible.Furthermore, the initiation of the array growth can be monitored accurately, as the catalyst strip is modified to half fill the gap between the sensing electrodes. Abrupt changes of current can be detected with pulse trains of short duty cycle supplied to the sensing electrodes when the CNT array grows out from one side of the sensing electrodes and reaches the counter electrode. With or without a delay right after the detection, a negative pulse with a width of 200 ms and a peak voltage of ?150 V is supplied to the responding electrodes to twist the chirality of the growing CNTs. As the result, the synthesized products are either high-purity semiconducting CNTs or intratube Schottky diode arrays. The positions of the intratube junctions can be tuned simply by applying a negatice pulse at different time delays. The time-resolved controllability of the intelligent synthesis approach is 20 to 100 times higher than that of the conventional methods.
